Prior to the manufacture and/or distribution of an electrical device (including a system or component such as a circuit board, integrated circuit, or system-on-a-chip (SOC)), the device is typically tested to determine whether it is built or functions as designed. Often, this testing is performed by automated test equipment (ATE, also called “testers”).
For the results of ATE to be meaningful, ATE needs to be calibrated. That is, the intrinsic system errors that ATE may introduce during testing under different conditions and test setups must be quantified. The data which quantifies ATE's intrinsic system errors is often referred to as “calibration data” and may comprise one or more “calibration factors”. Once generated, calibration data is used to remove ATE's intrinsic system errors from raw test data.
One way to characterize ATE's intrinsic system errors is to measure them directly. Often, this sort of calibration involves the coupling of various ATE probes to one or more known-good “calibration standards”, taking a measurement, and then comparing the measurement result to an expected measurement result.
Another way to characterize ATE's intrinsic system errors is to model them via a mathematic model. Calibration data may then be calculated from the model (although it may still be necessary to acquire certain measurements using one or more calibration standards).
Calibration data generally falls into two categories: 1) “system calibration data”, which characterizes the core structure of ATE (e.g., the instruments and base structures of ATE—typically those parts of the ATE that are re-used when testing different devices), and 2) “focused calibration data”, which characterizes the ATE under different test setups. Test setups may specify, for example, both the physical and electrical parameters under which testing will occur, including, for example, indications of the ATE test paths that will be used during testing, as well as their configuration (including, e.g., identifications of stimulus and/or measurement paths, and indications of which ATE pins will be coupled to which pins of a device); indications of testing frequencies (including, e.g., a test frequency range); indications of modulation formats; indications of measurement bandwidths; or indications of power or voltage levels.